130 AMERICAN SPECIES OF VERTIGO. 



teeth, occur in some places associated with both corpulenta 

 and with shells having the contour of typical modesta, the sub- 

 specific status can hardly be allowed this form. I conclude 

 that parietalis is the more primitive stock, and corpulenta a 

 mutation thereof, which has not obtained so wide a distribu- 

 tion. Typical V. modesta is a more cylindric form which has 

 mutated from long parietalis in the same way by loss of the 

 angular tooth; but as the five-toothed stock is not found east 

 of the Rocky Mountains, where modesta has a wide range, the 

 racial distinction may perhaps be retained. 



Fig. 4 is from an Ogden Canyon specimen. 



Professor Cockerell has reported a form from Tolland,. 

 Gilpin Co., Colorado, under the name V. m. parietalis, with 

 the following note "Rather small for parietalis, but over 

 2 mm. long; palatal plicae long, as is concinnula; shell clear 

 chestnut ; aperture strongly elbowed above. This is apparently 

 a distinct race, between parietalis and concinnula, but hardly 

 recognizable by a separate name. Ancey's name' ingersolli 

 certainly included such forms as this, and could be so re- 

 stricted without much risk of error" (Nautilus vol. 25, Sept., 

 1911, p. 59). 



See also under V. m. castanea, p. 134, for notes on parietalis 

 forms of the San Bernardino Mts., CaL, figured on p. 124, 

 figs. 8, So, 86. 



25c. Vertigo modesta corpulenta (Morse). PL 10, fig. 3. 



Shell rimate perforate, elongate ovate, finely striated, 

 polished, translucent, dark olive brown, apex round, obtuse; 

 whorls four, convex, tumid, wider at the base, aperture large, 

 sub-circular, with four obtuse teeth, one on the parietal mar- 

 gin, one on the columellar margin, and two on the labrum; 

 peristome slightly thickened and reflected. Length, .10 inch ; 

 breadth .06 inch (Morse). 



Nevada: Little Valley, Washoe Co., type loc., on the east 

 slope of the Sierra Nevada, 6500 ft. above the sea, R. E. 

 Stretch. 



Isthmia corpulenta MORSE, Am. Lye. Nat. Hist. N. Y., viii, 

 1865, p. 210, f. 7. Pupa corpulenta Morse, BINNEY, Land and 



